<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>声明变量案例</title>
</head>

<body>

    <p>点击这里来创建变量，并显示结果。</p>
    <button onclick="myFunction()">点击这里</button>
    <p id="demo"></p>
    <script>
        function myFunction() {
            var carname = "Volvo";
            document.getElementById("demo").innerHTML = carname;
        }
    </script>

</body>

</html>